The invention relates to a rotary actuator device for controlling the stroke of at least two equally acting gas charge exchange valves in a cylinder head of an internal combustion engine.
In German patent document DE 198 25 964 A1, a valve drive for an internal combustion engine is configured as a spring-and-mass vibrating system. It consists substantially of a rocker motor with a shaft running longitudinally in the cylinder head, as well as a lever-like exciter device for each gas charge exchange valve. The exciter devices can be coupled with the shaft according to the state of operation of the internal combustion engine. The rocker motor performs only a swiveling movement in the direction of a stroke of the gas charge exchange valve. The shaft and the exciter devices that can be coupled with it are a camshaft with releasable cams. At the end of each cam, at the point of contact with the gas charge exchange valve, a wheel is arranged so as to minimize friction. For all equally operating gas charge exchange valves, the valve drive has two rocker motors which are point-mirrored to one another, each with a corresponding camshaft.
Disadvantages of this embodiment are the great mass forces and the torques resulting therefrom which limit the maximum rotational speed of the internal combustion engine.
It is therefore a purpose of the present invention to reduce the driven masses in a valve drive.
This purpose is accomplished by a rotary actuator device that is used to control the stroke of at least two gas exchange valves in a cylinder head of an internal combustion engine. The device includes first and second actuating mechanisms, first and second rocker motors, and a force transfer element. Each actuating mechanism is provided for at least one of the gas exchange valves of the engine. The first rocker motor has a first shaft on which the first actuating mechanism is disposed, and the second rocker motor has a second shaft on which the second actuating mechanism is disposed. The first and the second rocker motors are arranged in a point-mirrored relationship. The force transfer element is disposed between each actuating mechanism and the at least one gas exchange valve.
Advantageously, the driven masses are reduced in the valve drive. By the reduction of the masses, the resultant moments and thus the mechanical stress on the entire valve drive are reduced, so that higher rotary speeds are possible. Furthermore, the internal friction of the valve drive is substantially reduced, with the result that the fuel consumption of the internal combustion engine decreases.
In a preferred embodiment, a compact, small drive unit for two cylinders is produced. This unit can be developed into a modular concept so that this unit can be used with any internal combustion engine whose number of cylinders per cylinder row is divisible by 2. Selective structural adaptation of the particular internal combustion engine is unnecessary in this modular configuration.
Further, both the inlet and outlet sides of the individual cylinder pairs are constructed with the same modular units. Manufacturing costs are lowered by this measure.
In another preferred embodiment, in the case of a bilateral construction of the valve operating device, both on the intake and on the outlet end, only one parallel displacement of the rotary actuator device needs to be performed. Further adaptive work at the cylinder head is unnecessary.
A further preferred embodiment serves to reduce friction in the valve operation combined with the absence of free play in the valve drive components. The support of the force transfer element, at one end on the hydraulic valve play equalizing element and on the other end on a gas exchange valve, reduces the driven masses, since in this arrangement the hydraulic valve antibacklash element can be located in the cylinder head, thus simultaneously assuring a reliable and simple oil supply. In comparison with the state of the art, in which a tappet is arranged between the turning means and the gas exchange valve, the cup is entirely absent in the configuration according to the invention, so that this mass is absent from the driven valve train.
To achieve a compact construction, the axes of the spark plug bores can be made closer together on the length of a device in order to obtain the smallest possible compact unit for the rotary actuator device, combined with invariably good conditions for the installation and removal of the ignition device, such as a spark plug, for example. The size of an apparatus is still further with this method in modular construction.
In a still further embodiment, in which the stator of the rocker motor extends radially around the rotor by at least 180°, since in such a configuration the stator surrounding the rotor does not extend over 360° radially at the circumference. In this embodiment the greatest component compactness is achieved.
The invention is further explained hereinbelow with the aid of a preferred embodiment in two figures.
The reference numbers in FIG. 1 apply to the same components in FIG. 2.